The proposed project will use transcleral microelectrode recording to electrophysiologically classify cat tetinal ganglion cells. Following electrophysiological classification, the ganglion cell will be intracellularly injected with horseradish peroxidase and, following histochemical processing, morphologically analyzed. Criteria for electrophysiological classification will include axonal conduction velocity, latency to stimulation of central sites, and receptive field analysis including size, type, surround, and spatial and temporal sensitivity. The data will yield structure/function correlations for retinal ganglion cells which will include morphological correlates of physiological types, and a number of parametric comparisons of morphological and physiological characteristics. The methodology proposed for these experiments is the only direct approach available for determining these correlations. The data acquired in these studies will define the normal structure/function relationships in the adult cat and can be used for comaprison in studies of the morphological and physiological development of the mammalian retina in normal and experimentally manipulated cats.